In dialogue mode, initialises the dialogue state, passing it the specified argument. For this to make sense, you need to have previously invoked the {\tt LOAD\_\-DIALOGUE} command, and the predicate {\tt initial\_\-dialogue\_\-state/2} needs to be defined. This predicate will be called to obtain the new dialogue state and perform any relevant initialisation. The argument to {\tt INIT\_\-DIALOGUE} is passed as the first argument, and the state is returned as the second argument.